Wireless communication networks are limited, with respect to range and coverage, by deterioration of signals to unacceptably weak levels. Indiscriminately boosting or amplifying signals by individual subscribers, however, causes interference that can render large portions of the network useless. Such interference causes harm to both the subscriber and the service provider. The subscriber loses the service that he or she originally hoped to enhance by signal boosting. The service provider loses revenue from unrealized connections and eventually from lost subscribers dissatisfied with poor service. What is needed is a communications booster that is sufficiently “smart” and foolproof to know when and where to amplify or not to amplify.
In particular, a smart communications booster must be able to sense where it is located with respect to geographic areas exhibiting strong or weak signal coverage. For example, in an area of strong coverage, a booster can cause overwhelming interference to base stations with an unnecessarily amplified signal. To prevent such interference, the smart booster must have continuous access to a coverage map so that it can compare its location with the known geographic areas of strong and weak coverage. Memory cards, which are essential parts of this invention, are the ideal way to provide a map. Further, such memory cards may be removable so that they can be revised or replaced as the areas of strong and weak coverage, and other attributes of the communications infrastructure, change over time. Alternatively, fixed memory devices inside a smart booster can be accessed from a port such as a USB (Universal Serial Bus) so that they may be similarly revised.
Methods presently exist to compensate for the deterioration of signals, with little or no attention to the interference those methods may cause. In the case of cellular and PCS communications networks, for example, four such methods are: 1) the use of bi-directional amplifiers, or BDAs; 2) the construction of additional base stations or the extension of base stations in the form of distributed antenna systems; 3) end-user deployment of femtocells, picocells, and microcells; and 4) the use of private subscriber high gain antennas.
The above methods are straightforward in principle. BDAs boost both uplink and downlink signals, without regard to signal strength. Additional base stations can provide service at locations where coverage was not previously available. Femtocells extend coverage into small regions such as home interiors by transferring the wireless link to the Internet. Individual subscribers can attach special purpose antennas to their transceivers that provide signal gain. All of these approaches, however, have significant disadvantages.
BDAs boost both uplink and downlink signals whether the subscriber is located far away from or in close proximity to a base station. In the latter case, the boosted uplink signal overwhelms the base station, rendering it effectively inoperative Countless connections are dropped or never completed so long as the subscriber equipped with a BDA remains in close proximity and the base station is disrupted by excess signal strength. BDAs cannot sense their locations with respect to base stations. BDAs are completely uncontrolled by service providers, leaving those providers unprotected. They cannot be remotely controlled, and so an adversely affected service provider cannot switch them off. It follows that BDAs cause substantial loss of revenue to service providers.
To address the above problem with BDAs, there have been attempts to make them adaptive, that is, automatically adjustable with respect to how much signal amplification is applied. For example, U.S. Pat. No. 7,409,186 describes a booster which adjusts its output power according to the intensity of signals received from nearby base stations. However, these nearby base station signals may not actually emanate from the subscriber's service provider. This results in “false positives”, which cause incorrect adjustment of the BDA. Additionally, such adaptation is unable to recognize regulatory constraints placed upon network providers requiring them to operate solely in certain geographic markets. As a result, the device indiscriminately amplifies signals outside of a carrier's licensed geographic market, and infringes upon the markets of other carriers.
Additional cell sites are not practical in many cases, especially at the very locations where they might do the most good. In marginal areas with few subscribers, the capital expenditure for a complete base station cannot be justified. In residential areas, restrictive zoning and public opposition may prevent the construction of new base stations.
Femtocells. picocells, and microcells are fundamentally different from signal boosters, with respect to both design and operation. They create an alternative network, in contrast to boosting the signal of an existing network connection. Instead of routing communications to nearby cellular base stations, calls are instead intercepted by femtocell devices and re-routed to the Internet. Further interaction with the cellular network is accomplished via the Internet, not via a wireless connection to a base station. It should be noted that when the Internet connection fails, for example, during a natural disaster or other emergency, the femtocell also fails. Femtocells are not transparent to all users. They must recognize the users by prearrangement. Further, those users are limited in number, typically to four. In contrast, a signal booster has no such limitations.
Further, in contrast to signal boosters, femtocells, picocells, and microcells are fundamentally unsuited to mobile operation because they must be tethered to the Internet. So, except within the confines of a small region, such as a home interior, they are not suitable for mobile use. They are certainly not suitable for mobile stations inside of vehicles and other wide ranging platforms.
Customized antennas for individual subscribers are generally not practical. They are by definition expensive compared with mass produced antennas. They require specialized engineering knowledge by the subscriber. For optimal results, they require timely knowledge of the cellular or PCS network, and that knowledge might not be available to the public. Generally, customized antennas are large and must be carefully oriented, and so they are not suitable for mobile stations. They will likely interfere with new base stations constructed in their vicinity. Where such construction eliminates the need for customized antennas, those antennas may become a new source of interference. Again because of size or elevation on a tall tower, customized antennas may be prohibited by zoning restrictions.